In an electronic apparatus with a scanning function, a contact image sensor module is widely used to scan graphs or texts. The scanned graphs or texts are converted into electronic signals for further processing operations such as transmission, display or storage. Referring to FIG. 1, a contact image sensor module 1 comprises a light source 11, a lens assembly 12 and a photosensing array 14 mounted on a substrate 13. During operation, the light beam emitted from the light source 11 is projected onto a document 15 to be scanned. The light beam reflected from the scanned document 15 is focused by the lens assembly 12. The focused light beam is then imaged onto the photosensing array 14. By means of the photosensing array 14, the optical signals indicative of colorful or grey scale changes for each scan line are successively converted into electronic signals, which are then processed into an image frame.
Please refer to FIG. 1 again. Since the photosensing array 14 comprises a linear array of discontinuous photosensing elements 14B of the same size, a gap P is present between two adjacent photosensing elements 14B. After the light beam reflected from the scanned document 15 and focused by the lens assembly 12, the photosensing array 14 fails to receive the optical signals completely and continuously. Therefore, an alternately dark and bright image, a discontinuous image or even a blank image occurs.